A video-on-demand (VOD) system is available that connects a video server in which video/audio information is stored and a user terminal over a network and that can provide video and audio from the video server to the user terminal in real time in accordance with a user's request.
In the VOD system, for example, the video server reads stored data in accordance with a request received from the user terminal and outputs a video/audio stream to the user terminal.
The user terminal receives the stream data transmitted from the video server and plays back the stream data. In addition, the user terminal plays back the received stream data while buffering it in a buffer so that transmission fluctuations due to network delay and so on occurred during transmission/reception of the stream data through the network can be absorbed so as to perform appropriate playback.
Thus, the user terminal plays back the stream data after data having an amount of data that allows playback is stored in the buffer.
A configuration in which a buffer is provided at the video server has also been developed (refer to Patent Document 1).    [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2003-209823